body{overflow:hidden;}

.back_bg{
	background-color: transparent;background-image: url('https://qiniu.kikuu.com/banner3.jpg');
	background-position: center 0;
	position: absolute;
	left: 0;
	top: 0;
	width: 100%;
	height: 600px;
}

.login{ height:200px;width:260px;padding: 20px;background-color:rgba(0,0,0,0.5);border-radius: 4px;position:absolute;left: 50%;top: 50%; margin:-150px 0 0 -150px;z-index:99;}
.login h1{ text-align:center; color:#fff; font-size:24px; margin-bottom:20px; }
.form_code{ position:relative; }·
.form_code .code{ position:absolute; right:0; top:1px; cursor:pointer; }
.login_btn{ width:100%; }